of lactic acid in the intestinal tract may exert a degree of anti-putrefactive action. It should, however, be remembered that there are persons with chronic inflammatory states of the digestive tract who tolerate very badly acids of all sorts. These persons are unable to take considerable quantities of fermented milk if the milk contains a high percentage of lactic acid, the attempt to utilize such food being followed by various unpleasant sensations and diarrhœa. The possible anti-putrefactive influence of the presence of living lactic acid bacilli in various parts of the digestive tract has already been discussed at sufficient length and it has been pointed out that this factor again is one whose value can not at present be accurately estimated.
It must be plain from what has been said that the therapeutic use of fermented milks rests at the present time rather more securely on the clinical observations that have been made with it than on an adequate scientific study of the influence exerted upon digestion and nutrition and especially on the processes of putrefaction. To obtain the necessary scientific data will require elaborate and very laborious experiments covering long periods of time. With the aid of such experiments I have no doubt that the usefulness of soured milks in health and in disease will be definitely and discriminatingly established. The limitations of utility will become equally plain, and I predict that they will prove to be many. The importance of this subject for the welfare of people at large not only in respect to immediate physical comfort and efficiency but as regards the prolongation of life, would, in my opinion, amply justify a very considerable expenditure of money to acquire this knowledge.
It can not be regarded as surprising that the enthusiasm which has been aroused partly through the public exploitation of various kinds of fermented milk in the treatment of disease and partly by the undoubted successes of the treatment should have led to various abuses. One of the most important things to understand in reference to the use of fermented milk is that it should be employed in most instances as a substitute for other forms of food rather than as an addition to the usual dietary. Especially is it necessary to bear this in mind in the case of chronic disorders associated with an increase in putrefaction. The addition of a considerable amount of fermented milk to the habitual dietary has often been practised with disastrous results, and I do not doubt that this practise is still widely extended. Such bad results might be predicted, for since all fermented milks contain a large proportion of protein material capable of undergoing putrefaction and since this putrefaction is not checked, in any specific way, through the agency of the fermented milk itself, a great increase of putrefactive decomposition may follow the injudicious excessive use
